Thermodynamic vs. kinetic control in the stereoselective intramolecular conjugate addition of amide enolates leading to chiral trans-3,4-disubstituted pyrrolidin-2-ones
✍ Scribed by Roberta Galeazzi; Giovanna Mobbili; Mario Orena
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- French
- Weight
- 825 KB
- Volume
- 55
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Intramolecular conjugate addition of amide enolates to ct,l~-unsaturated esters was found to give either of the diastereomeric trans-3,4-disubstituted pyrrolidin-2-ones 6, 10 or 7, 11 as the major products, by choosing the appropriate reaction conditions. The cyclisation performed with Nail in THF afforded mainly 6 and 10, whereas by using sodium ethoxide in ethanol the major products of the cyclisation were isomers 7 and 11, with the opposite configuration at both C-3 and C-4. This behaviour was explained by thermodynamic vs. kinetic control and supported by molecular mechanics and quantomechanical calculations.